(* ::Package:: *)

 


(* ::Section:: *)
(* RussianTrick *)


(* ::Text:: *)
(*`RussianTrick[exp, k, {q1, q2, p}]` (=RussianTrick[exp,p,p,{q1,q2,p}])` does the integration by parts where `p` is the external momentum.*)


(* ::Text:: *)
(*`RussianTrick[exp, k,l, {q1,q2,p}] (=RussianTrick[exp,k,l])` does integration by parts where `l` is the momentum to be differentiated.The result is an expression which is vanishing.*)


(* ::Subsection:: *)
(* See also *)


(* ::Text:: *)
(*FourDivergence, FourLaplacian.*)


(* ::Subsection:: *)
(* Examples *)


t=RHI[{2,0, 0,0, 0}, {1, 1, 1, 1, 1}]


t//RHI2FC
RussianTrick[%//RHI2FC,q2]
FC2RHI[%]
Solve2[%,t]
Clear[t]
